Go for the diesel, it's easier to maintain and causes a lot less hassle from a breakdown point of view than the petrol models as long as you service them regularly. I've been driving diesels since 1978, mainly Transit Campers and have never had a major breakdown. I've recently changed to a Fiat Ducato, (got a very good deal.)and find it very easy to drive and economical. There is a company not far from where I live who are installing waste cooking oil conversions which are very easy on fuel but thre is the drawback, as someone said earlier, of smelling like a chip shop.